Oil compositions



Patented Jan. 4, 1949 OIL COIVIPOSITION S Albert G. Rocchini, Springdale, Pa., assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application June 19, 1947, Serial No. 755,735

10 Claims. (Cl. 25233.6)

This invention relates to new and improved oil compositions, and in particular concerns mineral lubricating oil compositions having improved detergent and anti-corrosion properties and good oxidation stability.

At the present time it is common practice to enhance or modify certain of the properties of lubricating oils through the use of various additives or improvement agents. The lubricating oils employed in internal combustion engines, such as automotive, aviation, and Diesel engines, in particular require the use of additive agents to render them serviceable under the extreme conditions of temperature and pressure encountered in this type of engine. Among the various types of additives employed in such oils one of the most important is the type which acts to prevent slud e formation in the crank case, sticking of the piston rings, and the formation of vamish-like coatings on the pistons and cylinder walls. Because of their general cleansing action additives of this nature are termed detergents, although they are quite different chemically from the watersoluble detergents or wetting agents employed in aqueous media. Another important type of additive is the type which acts as an anti-corrosion agent to prevent rusting and corrosion of metal parts. Other commonly employed additive agents include anti-oxidants, extreme pressure agents, pour point depressants, and viscosity index improvers. All of such agents should efiect their respective improvements in the oil composition without adversely afiecting the desirable properties of the oil itself or interfering with one another. A

The present invention is based on the discovery of new additive agents in which are combined anti-corrosion, anti-oxidant, and detergent properties with respect to mineral oils. These agents are easily prepared from inexpensive starting materials, and are readily incorporated in mineral oils to form 011 compositions of improved performance characteristics. Such compositions display excellent resistance to sludging and varnish-formation in internal combustion engines operating under high performance conditions, and materially reduce ring-sticking, piston discoloration, etc., in such engines. These compositions also have excellent anti-corrosion properties in the presence of relatively large amounts of water or water vapor, and accordingly may be employed in steam turbines and the like as well as in internal combustion engines. They may likewise be employed as slushing oils or the like.

The invention thus consists of new oil composiamides of alkenyl-substituted succinic acids. The

substituted succinic acid amides from which such salts are prepared are obtained by initially reacting an olefine, such as amylene, hexylene, octylene, decylene, tetradecylene, etc., or a mixture of such olefines, such as occurs in refinery gases, with maleic anhydride in accordance with known procedure to obtain the corresponding alkenylsubstituted succinic acid anhydrides. The latter compounds are then reacted with an amine compound, such as ammonia, methylamine, diethylamine, aniline, propanolamine, phenylenediamine, cyclohexylamine, etc., to form the corresponding alkenyl-substituted succinic acid mono-amides. This reaction takes place at ordinary or only slightly elevated temperatures upon simple admixture of the reactants, and it may be employed to obtain a wide variety of alkenyl-substituted succinic acid mono-amides in which the alkenyl chain may contain from five to eighteen or even more carbon atoms, and the amino nitrogen may bear either one or two of a variety of neutral organic substituents, e. g. alkyl, alkylol, aralkyl, alkaryl, aryl, or cycloalkyl groups. These succinic acid amides may be defined by the general formula:

wherein R represents an alkenyl substituent, and X and Y each represents hydrogen or a neutral organic substituent. Any of such acid amides may be used in preparing the metal salts which ,the intermediate alkali-metal salt, the alkenylsuccinic acid mono-amide reactant is preferably first dissolved in an inert reaction medium, such as acetone, ethanol, etc., and the alkali-metal reactant is employed in the form of an alcoholate, such as sodium methylate, potassium ethylate, etc. The reaction takes place readily upon mixing the two reactants at room temperature or slightly above. If desired, the alkali-metal alkenyl-succinic acid amide salt product may be isolated in solid form and thereafter dissolved in water and reacted with an aqueous inorganic polyvalent metal salt to form the corresponding polyvalent metal salt of the amide, but ordinarily it is more convenient simply to add water to the reaction mixture, and then add an aqueous solution of a salt of the desired polyvalent metal. The double decomposition reaction takes place readily at ordinary temperatures, and the metal salt of the alkenyl-succinic acid amide formed in the reaction recipitates out of the aqueous solution, and may be filtered off and washed free of soluble contaminants. Any water-soluble poly- .valent metal salt may be employed in the double decomposition reaction, e. g. zinc chloride, calcium nitrate, barium chloride, nickel chloride, aluminum sulphate, strontium nitrate, cobalt nitrate, ferric chloride, magnesium sulfate, lead=nitrate, cadmium chloride, copper sulphate, chrmium chloride, antimony chloride, tin chloride, manganese chloride, etc., and any of the oilsoluble metal salts so obtained may be used in accordance with the invention. By reason of their low cost and general availability, however, the metals of groups II and VlII of the periodic system are usually preferred.

In compounding the improved oil compositions provided by the invention, the desired metal salt of the alkenyl-succinic acid amide is added to the desired oil base in an amount suflicient to secure the desired degree of improvement in service characteristics of the oil. This amount will accordingly depend upon the characteristics of the oil itself, as well as the conditions to which the composition is subjected in use. Ordinarily, however, the metal salt additive is employed in an amount representing between about 0.05 and about 5.0 per cent by weight of the entire composition. If the primary function of the additive is to impart anti-corrosion Properties to the base oil, as for example when the composition is to beemployed as a steam turbine lubricant or as a slushing oil, the amount of the additive is usually at the lower end of this range, e. g, 0.05-1.0 per cent.

On the other hand, if it is desired to emphasize detergent and sludge-resistant properties as well as anti-corrosion properties in the composition, as for example when it is to be employed in lubrieating heavy-duty asoline or Diesel engines, the

. base oil may contain other additive agents, such as viscosity index improvement agents, pour point depressants, extreme pressure agents, antifoam agents, etc. The nature of such additives and the proportion in which they are employed, as well as the characteristics of the base oil itself, will depend upon the use to which the composition is to be put, and the selection and compounding of base oils to provide compositions adapted for specific uses will be understood by those skilled in the art.

The following examples will illustrate several ways in which the principle of the invention has been applied, but are not to be construed as limiting the same.

Example I Approximately 181 parts by weight of dicyclohexylamine were added in small increments to approximately 250 parts by weight of mixed alkenyl-succinic acid anhydrides. The latter product was a light-yellow oily liquid commercial product obtainable by condensing a mixture of C10 to C12 olefines with maleic anhydride, and accordingly consisted essentially of a mixture of alkenyl-succinic acid anhydrides in which the alkenyl substituents contained an average of from 10 to 12 carbon atoms. Since the reaction with the dicyclohexylamine appeared to take place very slowly at room temperature, the mixture was heated to about 250 F. for about 5 minutes, whereby reaction took place readily to form mixed alkenyl succinic acid mono (dicyclohexyD- amides. The latter product was a dark reddishbrown, very viscous tacky liquid. Approximately 43 parts by weight of this product were dissolved in acetone, and approximately 6.8 parts by weight of sodium ethylate dissolved in ethyl alcohol were added with stirring. The sodium salts of the mixed alkenyl-succinic acid mono-(dicyclohexyD-amides thus formed partially precipitated from the acetone solution, and sufiicient distilled water was added to obtain a. clear solution. Approximately 14.6 parts of nickel nitrate dissolved in water were then added, whereby the nickel salts of the mixed alkenyl-succinic acid mono-(dicyclohexyl)-amides precipitated as a green fiocculent solid. This product was filtered ofi, dissolved in hexane, and washed several times with water to remove sodium nitrate. Evaporation of the hexane left the mixed dry metallic salts as a green resin-like oil-soluble sold. The following oil compositions were prepared:

The oil employed as the base oil in these compositions was a solvent-refined Mid-Continent oil of lubricating grade having-the following characteristics Gravity AP 28.3 Viscosity, SUS@ F 465 Viscosity, SUS@210 F 59.8 Viscosity index 88 Pour point "F -5 Neutralization No 0.01

of 13:1. At the end of 24 hours operation under these conditions the engine is stopped. disasembled, and the piston is examined as to stuck rings and discoloration. If there are no stuck rings, the engine is reassembled, the oil charge is brought up to 2.1 lbs., and operation is continued for another24-hour period. This procedure is repeated until one of the rings sticks or until a total of 216 operating hours has accrued. The piston color is rated on an arbitrary scale of 1 to representing increasing discoloration of the piston skirt. The data obtained in these tests on each of the above compositions is summarized as follows:

Composition I II III Piston Color No. of Stuck Rings Piston Color No. of Stuck Rings Piston Color Piston Color No. of stuck Rings Ri g! HOOOQOOQO HHOOOOQOQ It will be seen from these data that the addition of a relatively small proportion of one of the here= in-defined additives to a typical crankcase lubricant efiects an approximately four-fold increase in the time required for ring-sticking to occur in a Diesel engine.

Example II Approximately 43 parts by weight of the mixed alkenyl succinic acid mono (dicyclohexyD- amides prepared as described in Example I were dissolved in acetone, and approximately 6.8 parts by weight of sodium ethylate dissolved in ethyl alcohol were added with stirring. Water was added to the mixture until the cloudiness disappeared, and approximately 10.4 parts by weight of barium chloride dissolved in water were added. The barium salts of the mixed alkenyl-succinic acid mono- (dicyclohexyl) -amides which precipitated were filtered oif, dissolved in hexane, and washed with water. After removal of the hexane by evaporation, the mixed dry barium salts were obtained as a brownish tacky solid. A composition containing 98.5 per cent by weight of the base oil employed in Example I and 1.5 per cent by weight of the mixed barium salt product was tested in the Lauson engine as described in Example I. It was found that ring-sticking occurred only after 168 hours of engine operation.

Example III Approximately 43 parts by weight of the mixed alkenyl-succinic acid mono-(dicyclohexyD-amides prepared as described in Example I were dissolved in acetone and treated with 5.5 parts by weight of sodium methylate dissolved in methyl alcohol. The resulting sodium salt was taken up in water, after which approximately 6.8 parts by weight of zinc chloride dissolved in water were added with stirring. The zinc salt which precipitated was filtered off, dissolved in hexane, and washed with water, after which the hexane was evaporated off to obtain a lightbrown tacky solid consisting of the zinc salts of the mixed alkenyl-succinic acid mono-(dicyclohexyl) -amides. Approximately 0.5 part by No. of 2 6 weight of this product was dissolved in 99.5 parts by weight of a solvent-refined Mid-Continent lubricating oil, and the resulting composition was retained for anti-corrosion testing as described below. Example IV Example V calcium salt obtained was a light-brown tacky semi-liquid. A composition containing 0.5 part by weight of this product dissolved in 99.5 parts by weight of the base oil was prepared and retained for anti-corrosion testing.

The following table presents the physical characteristics of each of the oil compositions prepared as described in Examples III, IV, and V above and containing 0.5 per cent by weight of the zinc, aluminum, and calcium salts of the mixed alkenyl-succinic acid mono-(dicyclohexyl) -amides, respectively, together with comparative data on the base oil itself.

Composition Base Oil ifi Exagmle Gravity, API 28. 3 28. 4 28. 4 28. 4 Viscosity, SUS F 465 463 474 469 Viscosity, SUB @210 F 59. 8 60. 4 60. 2 59. 8 Viscosity Index 88 88 87 Pour Point, F 5 5 Flash Point, F 480 475 485 480 Fire Point, F 535 535 535 535 Neutralization N0. 0. 01 0. 25 0.50 0.01 Ash, perceut 0.01 0.07 0.03 0. 03 Color, NPA 2 2 2 2 I It will be noted from this data that the addition Example VI invention, the oil compositions prepared in Examples III, IV, V, and VI and a sample of the base oil itself were subjected to the following corrosion tests:

ASTM corrosion test.This test is that specifled in the ASTM Standards on Petroleum Products and Lubricants, September, 1945, and is designated as ASTM D-665-44T. In brief, the test consists in placing a 300 ml. sample of the oil or oil composition to be tested in a 400 ml. beaker which is immersed in a constant temperature bath maintained at F. The beaker is fitted with a cover provided with openings for a stainless steel motor-driven stirrer and for insertion of a standard steel test bar, inch in diameter and 5 inches long, which has been very carefully cleaned and polished just prior to the test. The stirrer is started, and'when the oil sample in the beaker reaches a steady temperature of 140 F. the test bar is inserted in the proper opening and hangs suspended from the beaker cover. After 30 minutes, 30 ml. of distilled water are added to the beaker, and stirring is continued for 48 hours, after which time the test bar is removed and examined for rust spots.

Film tenacity test-This test is designed to evaluate the corrosion resistance of a film of the oil composition as applied to steel surfaces. It is carried out immediately after the ASTM corrosion test described above. If the steel test bar used in the ASTM corrosion test shows no evidence of rusting, it is suspended in the mouth of a 300 ml. flask, and is allowed to drain. The beaker containing the oil sample is removed from the constant temperature bath, and is replaced with a clean beaker containing 300 ml. of distilled water. With the stirrer operating, the temperature of the water in the beaker is allowed to come up to 140 F., and when the test bar has drained for a period of 30 minutes, it is inserted in the beaker as before. Stirring is continued for 24 hours, after which the test bar is removed and examined for rust spots. It will be seen that this test is quite drastic since throughout its duration the steel test bar is protected from rusting only by a thin residual film of the oil composition under test. It not only evaluates the protection against rusting provided by the composition, but also indicates the tenacity with which a film of the composition adheres to metal surfaces.

Static drop test.The test specimen in this case is a 1 inch x 1 inch x A inch plate of SAE 1020 cold rolled steel having a shallow depression, 0.025 inch deep and 0.5 inch in diameter, machined in the center of one face. This specimen is very carefully cleaned and polished and is then degreased by boiling for a few minutes in benzene and for one minute in petroleum ether or ethyl ether. The specimen is then immersed as quickly as possible in a layer of the composition bein tested /2 inch deep in a 100 ml. beaker. The beaker is maintained at a constant temperature of 140 F., and after the oil and metal have been in contact for 1 hour at this temperature to attain adsorption equilibrium, one drop of distilled water is placed in the depression in the metal plate and underneath the surface of the oil with a pipette. The beaker is then covered with a watch glass, and is allowed to stand at the test temperature for 168 hours, after which the steel plate is removed from the oil and is examined for rust spots.

The results of these tests are summarized as While the preceding examples illustrate the preparation and employment according to the invention of a number of metal salts of mixed alkenyl succinic acid mono (dicycloheXyD- amides in which the alkenyl substituents contain an average of 10-12 carbon atoms, it is to be understood that other salts of this type may be similarly prepared and advantageously employed. The alkenyl substitutent in the succinic acid nucleus, for example, may be any alkenyl group containing 5 or more carbon atoms. Mixtures of alkenyl-succinic acid amides containing alkenyl substitutents of varying chain-length may likewise be employed. Similarly the amino nitrogen may bear a wide variety of mono-valent neutral organic substituents. Among the readily obtainable amines which may be reacted with alkenyl-succinic acids to form corresponding mono-amides suitable for use in preparing the metal salts employed as lubricating oil additives in accordance with the invention, there may be mentioned ammonia, dibutylamine, toluidine, phenetidine, alpha-naphthylamine, phenylethylamine, cyclohexylamine, aniline, ethanolamine, diethanolamine, diphenylamine, butylamine, amylamine, benzylamine, etc.

Other modes of applying the principle of my invention may be employed instead of those explained, change being made as regards the ingredients or methods employed, provided the compositions stated by any of the following claims, or the equivalent of any such stated compositions, be obtained.

I, therefore, particularly point out and distinctly claim as my invention:

1. An oil composition consisting essentially of a major proportion of a mineral oil and a minor proportion sufilcient to improve the detergent, anti-oxidant, and anti-corrosion characteristics of said mineral oil of an oil-soluble polyvalent metal salt of an alkenyl-succinic acid monoamide in which the alkenyl group contains from 5 to 18 carbon atoms.

2. A lubricating oil composition consisting essentially of a major proportion of a mineral oil of lubricating viscosity and from about 0.05 to about 5.0 per cent'by weight of oil-soluble polyvalent metal salts of mixed alkenyl-succinic acid mono-amides in which the alkenyl-substituents contain from 10 to 12 carbon atoms.

3. A lubricating oil composition consisting essentially of a major proportion of a. mineral oil of lubricating viscosity and from about 0.05 to about 5.0 per cent by weight of oil-soluble polyvalent metal salts of mixed alkenyl-succinic acid mono-(dicyclohexyl)-amides in which the alkenyl-substituents contain from 10 to 12 carbon atoms.

4. A lubricating oil composition consisting essentially of a major proportion of a mineral oil Oflubricating viscosity and from about 0.05 to about 5.0 per cent by weight of nickel salts of mixed alkenyl-succinic acid mono-amides in which the alkenyl substituents contain from 10 12 carbon atoms.

5. A lubricating oil composition consisting essentially of a major proportion of a mineral oil of lubricating viscosity and from about 0.05 to about 5.0 per cent by weight of barium salts of mixed alkenyl-succinic acid mono-amides in which the alkenyl substituents contain from 10 to 12 carbon atoms.

6. A lubricating oil composition consisting essentially of a major proportion of a mineral oil of lubricating viscosity and from about 0.05 to 8. A lubricating oil composition consisting essentially of a major proportion of a mineral oil of lubricating viscosity and from about 0.05 to about 5.0 per cent by weight of barium salts 10 of lubricating viscosity and at least 0.05 per cent by weight of an oil-soluble polyvalent metal salt of an alkenyl-succinic acid mono-amide in which the alkenyl group contains 6 to 12 carbon atoms.

ALBERT G. ROCCHINI.

REFERENCES CITED The following references are of record m the file of this patent:

UNITED STATES PATENTS Number Name Date 1,870,074 Sullivan Aug. 2, 1932 2,292,308 Watkins Aug 4, 1942 15 2,363,516 Farrington Nov.'28, 1944 

